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Publication numberUS5564086 A
Publication typeGrant
Application numberUS 08/158,551
Publication dateOct 8, 1996
Filing dateNov 29, 1993
Priority dateNov 29, 1993
Fee statusPaid
Publication number08158551, 158551, US 5564086 A, US 5564086A, US-A-5564086, US5564086 A, US5564086A
InventorsLawrence F. Cygan, Paul H. Gailus, William J. Turney, Francis R. Yester, Jr.
Original AssigneeMotorola, Inc.
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and apparatus for enhancing an operating characteristic of a radio transmitter
US 5564086 A
Abstract
In a radio transmitter (100) that includes a power amplifier (104) and an antenna (106), a method for enhancing an operating characteristic of the radio transmitter (100) can be accomplished in the following manner. The power amplifier (104) provides a signal (113) to a variable matching network (111), wherein the signal (113) comprises energy to be radiated by the antenna (106). The variable matching network (111) couples the signal (113) to a sampler (112) that is operably coupled to an output of the variable matching network (111 ) and the antenna (106). The sampler (112) samples a forward component (114) and a reflected component (115) of the signal (113). The radio transmitter (100) processes the sampled forward and reflected components (116, 118) to produce a feedback control signal (120). The feedback control signal (120) is used to adjust the variable matching network (111 ), such that an operating characteristic of the radio transmitter (100) is enhanced.
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Claims(15)
We claim:
1. In a radio transmitter that includes a power amplifier and an antenna, a method for enhancing an operating characteristic of the radio transmitter in an environment of varying antenna loads, the method comprising the steps of:
A) providing a signal, by the power amplifier, wherein the signal comprises energy to be radiated by the antenna;
B) coupling, by a variable output matching network of the power amplifier, the signal to a sampler that is operably coupled to an output of the variable output matching network and the antenna;
C) sampling, by the sampler, a forward component of the signal to produce a sampled forward component;
D) sampling, by the sampler, a reflected component of the signal to produce a sampled reflected component;
E) processing the sampled forward component and the sampled reflected component to produce a feedback control signal; and
F) using the feedback control signal to adjust the variable output matching network of the power amplifier to compensate for the varying antenna loads.
2. The method of claim 1, wherein step (A) comprises the step of providing a plurality of time division multiple access (TDMA) time frames, each of the plurality of TDMA time frames including a plurality of information bearing time slots.
3. The method of claim 2, wherein step (A) further comprises the step of partitioning at least one of the plurality of information bearing time slots into a training portion and an information portion to produce at least one partitioned information bearing time slot.
4. The method of claim 3, wherein step (C) comprises the step of sampling a forward component of the at least one partitioned information beating time slot at a time substantially within the training portion to produce the sampled forward component.
5. The method of claim 3, wherein step (D) comprises the step of sampling a reflected component of the at least one partitioned information bearing time slot at a time substantially within the training portion to produce the sampled reflected component.
6. The method of claim 2, wherein step (A) further comprises the step of providing the plurality of TDMA time frames, each of the TDMA time frames including a plurality of non-information bearing time slots.
7. The method of claim 6, wherein step (F) comprises the step of conveying the feedback control signal to the variable matching network at a time corresponding to at least one of the plurality of non-information bearing time slots.
8. The method of claim 10, wherein step (D) comprises the step of sampling the reflected component of the at least one partitioned information beating time slot at a time substantially within the training portion to produce the sampled reflected component.
9. The method of claim 7, wherein step (D) comprises the step of sampling the reflected component of the at least one partitioned information bearing time slot at a time substantially within the training portion to produce the sampled reflected component.
10. The method of claim 7, wherein step (C) comprises the step of sampling the forward component of the at least one partitioned information beating time slot at a time substantially within the training portion to produce the sampled forward component.
11. A radio transmitter that includes a power amplifier and an antenna for radiating an information bearing signal, the, radio transmitter operating in an environment of varying antenna loads, the radio transmitter comprising:
a variable output matching network of the power amplifier;
sampling means, operably coupled to an output of the variable output matching network and the antenna, for sampling a forward component of the information bearing signal to produce a sampled forward component and a reflected component of the information bearing signal to produce a sampled reflected component;
signal processing means, operably coupled to the sampling means, for processing the sampled forward component and the sampled reflected component to produce a control signal; and
feedback means, disposed between the signal processing means and the variable output matching network, for coupling the control signal to the variable output matching network to compensate for the varying antenna loads.
12. The radio transmitter of claim 11, Wherein the sampling means comprises a directional coupler.
13. The radio transmitter of claim 11, wherein the variable matching network comprises at least one varactor diode and at least one transmission line.
14. The radio transmitter of claim 11, wherein the signal processing means comprises a read-only memory.
15. In a radio transmitter that includes a power amplifier and an antenna, a method for enhancing an operating characteristic of the radio transmitter in an environment of varying antenna loads, the method comprising the steps of:
A) providing a plurality of time division multiple access (TDMA) time frames, each of the plurality of TDMA time frames including a plurality of information bearing time slots and a plurality of non-information bearing time slots, at least one of the plurality of information bearing time slots being partitioned into a training portion and an information portion to produce at least one partitioned information bearing time slot, wherein the plurality of information bearing time slots comprise energy to be radiated by the antenna;
B) coupling, by a variable output matching network of the power amplifier, the plurality of TDMA time frames to a sampler that is operably coupled to an output of the variable output matching network and the antenna;
C) sampling, by the sampler, a forward component of the at least one partitioned information bearing time slot at a time substantially within the training portion to produce a sampled forward component;
D) sampling, by the sampler, a reflected component of the at least one partitioned information bearing time slot at a time substantially within the training portion to produce a sampled reflected component;
E) processing the sampled forward component and the sampled reflected component to produce a feedback control signal; and
F) conveying the feedback control signal to the variable output matching network at a time corresponding to the plurality of non-information bearing time slots to adjust the variable output matching network to compensate for the varying antenna loads.
Description
FIELD OF THE INVENTION

The present invention relates generally to radio frequency transmitters and, in particular, to a linear radio frequency transmitter having a varying antenna load.

BACKGROUND OF THE INVENTION

As is known, radio frequency (RF) transmitters modulate baseband signals, such as analog voice or digital voice samples, onto an RF carrier, amplify the RF carder, and transmit the RF carrier, via an antenna, through the air as electromagnetic energy. The electromagnetic energy is subsequently received by a receiver's antenna, demodulated back to the baseband signal, and reconstructed into its original form by the receiver.

As is also known, many communication systems, such as cellular telephone and thinking systems, utilize spectrally efficient modulation techniques, such as quadrature amplitude modulation (QAM) and quaternary phase shift keying (QPSK), in a time division multiple access (TDMA) format. These spectrally efficient modulation techniques typically correlate the baseband signal to changes in RF carder amplitude and phase via a digital symbol constellation format. Since the spectrally efficient modulation techniques require variation of the RF carder amplitude, a linear class A or class AB amplifier must be used. If the amplifier is non-linear, it provides unwanted RF energy, or splatter, at frequencies adjacent to the RF carder. This splatter may subsequently interfere with two-way communications in process on the adjacent frequencies, or channels.

Linearity of a power amplifier is affected by the varying load impedances presented by the radio transmitter's antenna. Typically, an antenna is designed to provide a fixed load impedance, 50 ohms for example. However, due to the proximity of the antenna to highly reflective objects, such as automobiles or metal walls, the antenna impedance changes.

To minimize variations in power amplifier loading, transmitters generally incorporate isolators to provide a substantially constant load impedance to the amplifier. The isolator includes a circulator and a terminating impedance, which is typically 50 ohms. The circulator is a three-terminal device that provides unidirectional flow of the RF energy--i.e., from the amplifier to the antenna, and from the antenna to the terminating impedance. Therefore, the RF energy sourced by the amplifier is provided to the antenna and any RF energy reflected by the antenna is absorbed in the terminating impedance. In this manner, the isolator presents a constant impedance to the RF power amplifier irrespective of the antenna load impedance.

Although the isolator provides a constant load impedance, other factors--e.g., size, cost, and bandwidth limitations--typically inhibit the use of a universal isolator in mobile radios, portable radios, and cellular telephones. For example, a radio that operates at 132 MHz requires an isolator that has a volume of 8.19 cubic centimeters (0.5 cubic inches), weighs 227 grams (0.5 pounds), and costs at least $30/unit. As a result, an isolator puts undesired size, weight, and cost constraints on the design of such radios. Additionally, isolators have fixed bandwidths; therefore, multiple isolators may be required in transmitters that operate over a wide frequency range. This bandwidth limitation is most noticeable at lower RF carrier frequencies, such as VHF, where the allocated frequency band covers a large percentage bandwidth. Further, the isolator dissipates a considerable amount of RF energy when the antenna presents a highly reflective load impedance. This energy dissipation negatively impacts the net gain and efficiency of the radio transmitter.

To avoid the use of the isolator, existing frequency modulation (FM) transmitters, which employ nonlinear amplifiers, typically utilize protective feedback circuitry. The protective feedback circuitry monitors the voltage standing wave ratio (VSWR) at the nonlinear amplifier's output, and correspondingly reduces the mount of output power provided by the nonlinear amplifier to the antenna. This approach typically reduces the nonlinear amplifiers output power by a fixed mount when the VSWR exceeds a predetermined level. For example, when a 3:1 VSWR is detected at the nonlinear amplifier's output, the output power may be reduced by 3 dB. Although this approach works for nonlinear amplifiers, it does not include any provisions for maintaining amplifier linearity under high VSWR load conditions. Thus, this simple power reduction approach is not readily applicable for use in a linear amplifier.

Alternatively, a known method for detecting and correcting impedance mismatches may be used to obviate the use of an isolator in an FM transmitter. This method--as described in U.S. Pat. No. 4,704,573, entitled "Impedance Mismatch Detector" and assigned to Motorola, Inc.--allows impedance mismatches between the amplifier and the antenna to be measured and adaptively corrected during changes in operating conditions of the amplifier. Although this method provides a technique for electronically correcting poor loads presented to an amplifier, it is not readily adaptable for use in a linear transmitter since it does not provide means for changing the amplifier's load without influencing important linear performance parameters, such as adjacent channel splatter.

Therefore, a need exists for a method to enhance operating characteristics of a linear transmitter that operates under varying antenna loads without having to use an isolator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a radio transmitter, in accordance with the present invention.

FIG. 2 illustrates a preferred data stream comprising time division multiple access (TDMA) time frames, in accordance with the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

Generally, the present invention provides a method and apparatus for enhancing an operating characteristic of a radio transmitter. A power amplifier provides a signal to a variable matching network, wherein the signal comprises energy to be radiated by an antenna. The variable matching network couples the signal to a sampler that is operably coupled to an output of the variable matching network. The sampler samples forward and reflected components of the signal and provides these samples to a processor. The processor then processes the sampled forward and reflected components to produce a feedback control signal. The feedback control signal is used to adjust the variable matching network, such that an operating characteristic of the radio transmitter is enhanced. By providing the transmitter operating characteristic enhancement in this manner, the power amplifier maintains acceptable performance, despite varying antenna loads, without requiring an isolator between the amplifier output and the antenna, as in prior an transmitters.

The present invention can be more fully described with reference to FIGS. 1 and 2. FIG. 1 illustrates a radio transmitter 100 that includes a signal source 102, a power amplifier 104, an antenna 106, a processor 110, a variable matching network 111, and a directional coupler 112, in accordance with the present invention. The variable matching network 111 preferably comprises voltage variable capacitors (e.g., varactor diodes) and other discrete, or distributed, reactive elements--such as inductors, capacitors, and/or transmission lines. The directional coupler 112 is well known, and typically comprises a pair of coupled transmission lines, or a coupled inductor/capacitor topology that can determine the directional flow of a radio frequency (RF) signal.

In a preferred embodiment, the signal source 102 comprises a digital signal processor (DSP) and circuitry necessary to upconvert the digital baseband output of the DSP to an RF signal. However, in alternate transmitters, the signal source 102 may comprise a variety of known modulators, such as an amplitude modulator or a frequency modulator, and their associated upconverting circuitry. In the preferred embodiment, the power amplifier 104 comprises a linear class A RF power amplifier, but other amplifier topologies may also be employed, such as linear class AB or nonlinear class C. The processor 110 includes a memory 122, such as a read only memory (ROM), and may comprise a DSP, a microprocessor, or any combination thereof that provides means for processing its input signals.

General operation of the radio transmitter 100 occurs in the following manner. The signal source 102 provides an input energy signal to the power amplifier 104. The input energy signal preferably comprises a plurality of time division multiple access (TDMA) time frames, as described below. However, the input signal may also comprise any modulated signal used for radio communications.

The power amplifier 104 amplifies the input energy signal and provides an amplified signal 113 at its output. The amplified signal 113 is applied to the variable matching network 111, which transforms the load impedance presented to the power amplifier 104, without introducing significant signal attenuation. The amplified signal 113 exits the variable matching network's output and proceeds through the directional coupler 112 to the antenna 106 where it is radiated as electromagnetic energy.

The degree to which the amplified signal 113 is radiated from the antenna 106 is dependent upon the impedance of the antenna 106. The antenna 106 is generally designed to provide a predetermined nominal input impedance (e.g., 50 ohms) when the antenna 106 is located in an environment that approximates free space. However, the antenna's input impedance is greatly affected by the physical environment in which it is located. In a practical environment, the antenna impedance deviates from its design value due to the presence of reflective structures positioned in close proximity to the antenna 106. For example, portable radio antennas are often used near metal buildings and walls in urban environments. The result of using the antenna 106 near reflective objects is a significant variation in the antenna's input impedance. Thus, when operated near reflective structures, the antenna 106 radiates only a portion of the amplified signal 113. The portion that is not radiated re-enters the antenna 106 as reflected energy 115.

The directional coupler 112 provides a means of sampling forward 114 and reflected 115 components of the amplified signal 113 without significantly attenuating the amplitude of the amplified signal 113. The directional coupler 112 extracts a small portion (typically less than 10%) of the forward and reflected components 114, 115 to produce a sampled forward component 116 and a reflected component 118, respectively. The exact portion extracted is chosen to provide samples 116, 118 having signal-to-noise ratios suitable for further processing. Typically, the directional coupler 112 utilizes substantially identical scaling factors to sample both the forward and reflected components 114, 115; however, non-identical sampling may also be performed.

In a preferred embodiment, the directional coupler 112 provides its samples 116, 118 in sinusoidal form to the processor 110 for further processing. The processor 110 transforms the samples 116, 118 to a digital format using an analog-to-digital (A/D) conversion technique, and then computes a ratio of the reflected sample 118 to the forward sample 116. Since the samples 116, 118 are sinusoidal, the computed ratio contains both a magnitude component and a phase component. This vector quantity-well known in the art as the reflection coefficient-provides a direct correspondence to the power amplifier load impedance presented by the antenna 106. Once computed, the reflection coefficient may also be used in a known manner to calculate the particular impedance presented to the antenna 106. Since both the reflection coefficient and the antenna's input impedance uniquely correspond to the load condition present at the antenna 106, the processor 110 may use either quantity to generate a feedback control signal 120. For the remainder of this discussion, it is assumed that the processor 110 computes the reflection coefficient.

After computing the reflection coefficient, the processor 110 compares the reflection coefficient to data contained in its memory 122. The data--i.e., a so-called 10ok-up table of various reflection coefficients and corresponding feedback control signals 120--is preferably entered into memory 122 when the radio transmitter 100 is manufactured. In this manner, the processor 110 retrieves the feedback control signal 120 that corresponds to the computed reflection coefficient and applies it to the variable matching network 111. The feedback control signal 120 is preferably a DC voltage that is subsequently applied to a varactor diode in the variable matching network 111. However, the feedback control signal 120 may be either an analog or digital waveform, depending on the construction of the variable matching network 111.

In an alternate embodiment, the look-up table may be replaced by a mathematical system of equations that uses the reflection coefficient, or the antenna impedance, to provide the feedback control signal 120 directly, without the need for extensive data storage. It should also be noted that, although a preferred embodiment of the present invention utilizes the directional coupler 112 to provide forward and reflected component samples 116-118, alternate quantities may be sampled by the radio transmitter 100. For example, measurement of the DC current drawn by the power amplifier 104 may be substituted for the reflected sample 118 in some applications. In this case, the feedback control signal 120 is generated based on the measured DC current.

As briefly mentioned above, the feedback control signal 120 is applied to the variable matching network 111 to adjust the impedance transformation provided by the variable matching network 111 in response to changes in the loading condition of the antenna 106. The variable matching network 111 receives the feedback control signal 120 via a wire, a printed circuit board trace, or any other equivalent means for providing an analog or digital control signal. In this way, the variable matching network 111 dynamically corrects the mismatch between the output impedance of the power amplifier 104 and the input impedance of the directional coupler 112 caused by changes in the antenna load impedance. By correcting this impedance mismatch, the present invention enhances an operating characteristic of the radio transmitter 100--such as power amplifier linearity, energy transfer between the power amplifier 104 and the antenna 106, or power amplifier gain--in the presence of varying antenna loads.

One particularly significant aspect of the present invention lies in the structural composition and orientation of the variable matching network 111 and the directional coupler 112. As depicted in FIG. 1, the variable matching network 111 precedes the directional coupler 112, or sampler. This configuration enables the variable matching network 111, via the feedback control signal 120, to present a constant load impedance, or desired load mismatch, to the power amplifier 104 during variation of antenna loading, while preserving the information of the amplified signal samples 116, 118. The ability of the present invention to create a particular load at the power amplifier's output allows the radio transmitter 100 to maintain, or improve, key performance characteristics, such as gain, linearity, and efficiency, to attain a predetermined operating condition (e.g., enhanced linearity or gain) or to operate under varying antenna loads. By contrast, prior art methodologies transpose the order of the variable matching network 111 and the directional coupler 112. This approach allows a constant load impedance to be presented to the power amplifier 104 during changes in antenna loading, but does not facilitate computation of an antenna load reflection coefficient due to the reflected sample's dependence on the response of the variable matching network 111. Thus, the present invention, unlike the prior art, is capable of adaptively generating desired power amplifier loads via its variable matching network 111 and, accordingly, may be utilized to enhance key transmitter performance characteristics in response to changes in antenna loading.

FIG. 2 illustrates a preferred data stream comprising TDMA time frames 201-204, each frame including six time slots, in accordance with the present invention. The time slots may be information bearing time slots (e.g., 205, 212), or non-information beating time slots (e.g., 207, 213). Depending on radio communication system configuration, a variety of information beating and non-information beating time slot combinations may be utilized to transmit information. For example, a time frame 201 may include a single information bearing time slot 205 and a plurality of non-information bearing time slots 207. Alternatively, time frames 202-203 may include multiple information beating and non-information bearing time slots. Further, another time frame 204 may comprise only non-information beating time slots--e.g., silence.

The information bearing time slot 205 is partitioned into a training portion 209 and an information portion 211. Sampling of the forward and reflected components 114-115 of the amplified signal 113, as earlier described, is preferably performed during the training portion 209. In a linear transmitter of the type detailed in U.S. Pat. No. 5,066,923, entitled "Linear Transmitter Training Method And Apparatus," and assigned to Motorola, the training portion 209 is used to dynamically adjust transmitter operating parameters that affect linearity prior to transmission of the information portion 211. Thus, by sampling the amplified signal 113 during the training portion 209, the present invention avoids using time allocated for transmitting the information portion 211 to perform the sampling, thereby preserving data transmission efficiency. It should be noted that sampling during the information portion 211 is possible, though not desirable, since its random nature may require lengthy time averaging of the samples 116, 118, thus producing significant computational delays in the processor 110.

Once the sampled forward and reflected components 116, 118 are obtained, the radio transmitter 100 preferably uses the non-information beating time slots 207, 213 to process the sampled components 116, 118, generate the feedback control signal 120, and adjust the tunable elements of the variable matching network 111. During the non-information bearing time slots 207, 213, the signal processing facilities (e.g., 110) of the radio transmitter 100 are utilized less than during information bearing time slots 205, 212. Thus, by using the time corresponding to non-information bearing time slots 207, 213 to process the sampled components 116, 118, generate the feedback control signal 120, and adjust the variable matching network 111, the present invention effectively equalizes the processing load of the processor 110, thereby reducing processor hardware and current drain requirements. Further, by performing the aforementioned functions during the non-information bearing time slots 207, 213, the present invention obviates generating adjacent channel splatter that may be produced by adjusting the variable matching network 111 during the information beating time slots 205, 212.

The present invention provides a method and apparatus for enhancing an operating characteristic of a radio transmitter. With this invention, transmitter performance may be dynamically optimized and maintained without utilization of an isolator between the power amplifier and the antenna. Further, the present invention allows rapid adjustment of the power amplifier's output matching network in response to varying antenna loads without generating adjacent channel interference, a feature that is unavailable using prior art matching network adjustment techniques.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US4246535 *Jul 6, 1979Jan 20, 1981Rca CorporationDesign method for linear amplifier
US4493112 *Nov 19, 1981Jan 8, 1985Rockwell International CorporationAntenna tuner discriminator
US4704573 *Nov 22, 1985Nov 3, 1987Motorola, Inc.Impedance mismatch detector
US4985686 *Dec 4, 1989Jan 15, 1991Motorola, Inc.Active load impedance control system for radio frequency power amplifiers
US5066923 *Oct 31, 1990Nov 19, 1991Motorola, Inc.Linear transmitter training method and apparatus
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US5777475 *Dec 6, 1994Jul 7, 1998Siemens AktiengesellschaftAutomatic impedance adapter for a H.F. emitter or receiver in a nuclear spin tomography installation and process for operating the device
US5778308 *Dec 26, 1996Jul 7, 1998Nokia Mobile Phones LimitedAdaptive antenna matching
US5862458 *Apr 17, 1996Jan 19, 1999Nec CorporationImpedance matching circuit in transmitter circuit and control method thereof
US5898912 *Jul 1, 1996Apr 27, 1999Motorola, Inc.Direct current (DC) offset compensation method and apparatus
US5913154 *Apr 18, 1997Jun 15, 1999Ericsson, Inc.Rf device
US5999134 *Dec 19, 1996Dec 7, 1999Ppg Industries Ohio, Inc.Glass antenna system with an impedance matching network
US6018646 *Aug 22, 1997Jan 25, 2000Nokia Mobile Phones LimitedPower consumption monitor and alarm for a mobile means of communication
US6069538 *Nov 25, 1998May 30, 2000Murata Manufacturing Co., Ltd.Impedance stabilizing unit and high-frequency module using the unit
US6122490 *Feb 2, 1998Sep 19, 2000Crosslink, Inc.System for ensuring type acceptance requirements and enhancing equipment capabilities in a RF system
US6138042 *Dec 31, 1997Oct 24, 2000Motorola, Inc.Method, device, phone, and base station for providing an efficient tracking power converter for variable signals
US6141541 *Dec 31, 1997Oct 31, 2000Motorola, Inc.Method, device, phone and base station for providing envelope-following for variable envelope radio frequency signals
US6160449 *Jul 22, 1999Dec 12, 2000Motorola, Inc.Power amplifying circuit with load adjust for control of adjacent and alternate channel power
US6166598 *Jul 22, 1999Dec 26, 2000Motorola, Inc.Power amplifying circuit with supply adjust to control adjacent and alternate channel power
US6178310 *Dec 29, 1997Jan 23, 2001Lg Information & Communications, Ltd.Transmitting and receiving antenna voltage standing wave ratios measuring circuit of base station in mobile communication system
US6281748Jan 14, 2000Aug 28, 2001Motorola, Inc.Method of and apparatus for modulation dependent signal amplification
US6297696Jun 15, 2000Oct 2, 2001International Business Machines CorporationOptimized power amplifier
US6310579 *May 12, 2000Oct 30, 2001Radio Frequency Systems, Inc.Method and apparatus for calibrating antenna apparatus and testing an antenna connected thereto
US6337975 *Aug 31, 1999Jan 8, 2002Qualcomm Inc.System and method for power measurement in outdoor antenna units
US6349216Jul 22, 1999Feb 19, 2002Motorola, Inc.Load envelope following amplifier system
US6362690Apr 19, 2000Mar 26, 2002Ophir Rf, Inc.System and method for closed loop VSWR correction and tuning in RF power amplifiers
US6414562 *May 27, 1997Jul 2, 2002Motorola, Inc.Circuit and method for impedance matching
US6438360Jul 22, 1999Aug 20, 2002Motorola, Inc.Amplifier system with load control to produce an amplitude envelope
US6538506Aug 21, 2001Mar 25, 2003Sony CorporationMatching apparatus
US6570462 *May 29, 2001May 27, 2003Research In Motion LimitedAdaptive tuning device and method utilizing a surface acoustic wave device for tuning a wireless communication device
US6577850 *Sep 5, 2001Jun 10, 2003Nec CorporationBooster for amplifying the transmission output of a handy phone
US6587014Jan 25, 2001Jul 1, 2003Paradigm Wireless Communications LlcSwitch assembly with a multi-pole switch for combining amplified RF signals to a single RF signal
US6597244Feb 5, 2002Jul 22, 2003Ophir Rf, Inc.System and method for closed loop VSWR correction and tuning in RF power amplifiers
US6710651 *Oct 22, 2001Mar 23, 2004Kyocera Wireless Corp.Systems and methods for controlling output power in a communication device
US6751448Oct 13, 1999Jun 15, 2004Intel CorporationControl of transmission power in a communication system
US6825794May 23, 2001Nov 30, 2004Research In Motion LimitedWireless communication system using surface acoustic wave (SAW) second harmonic techniques
US6845126 *Apr 25, 2003Jan 18, 2005Telefonaktiebolaget L.M. Ericsson (Publ)System and method for adaptive antenna impedance matching
US6895225Mar 29, 2000May 17, 2005Nokia Mobile Phones, Ltd.System for matching an antenna for a wireless communication device
US6934557Sep 27, 2002Aug 23, 2005Kabushiki Kaisha ToshibaPortable type radio equipment
US6961368 *Jan 26, 2001Nov 1, 2005Ericsson Inc.Adaptive antenna optimization network
US6965837 *Oct 10, 2003Nov 15, 2005Nokia CorporationMethod and arrangement for detecting load mismatch, and a radio device utilizing the same
US7035609 *Sep 24, 2001Apr 25, 2006Fry Terry LMethod and apparatus for automatically identifying an antenna connected to a radio transmitter and for automatically controlling a transmitter
US7039373 *Feb 5, 2001May 2, 2006Matsushita Electric Industrial Co., Ltd.Wireless communication apparatus and transmission power control method thereof
US7054739 *May 1, 2003May 30, 2006Honeywell International Inc.Radio navigation system
US7058372 *Nov 1, 2002Jun 6, 2006Integration Associates Inc.Method and apparatus for automatic tuning of a resonant loop antenna
US7071776 *Mar 22, 2004Jul 4, 2006Kyocera Wireless Corp.Systems and methods for controlling output power in a communication device
US7116954Nov 5, 2004Oct 3, 2006Kyocera Wireless Corp.Tunable bandpass filter and method thereof
US7127220Dec 23, 2002Oct 24, 2006Spectrasite Communications IncApparatus and method to monitor and control power
US7154440Feb 16, 2005Dec 26, 2006Kyocera Wireless Corp.Phase array antenna using a constant-gain phase shifter
US7164329Apr 10, 2002Jan 16, 2007Kyocera Wireless Corp.Tunable phase shifer with a control signal generator responsive to DC offset in a mixed signal
US7174147Feb 16, 2005Feb 6, 2007Kyocera Wireless Corp.Bandpass filter with tunable resonator
US7176845Jul 26, 2004Feb 13, 2007Kyocera Wireless Corp.System and method for impedance matching an antenna to sub-bands in a communication band
US7180467Jul 26, 2004Feb 20, 2007Kyocera Wireless Corp.System and method for dual-band antenna matching
US7184727Jul 26, 2004Feb 27, 2007Kyocera Wireless Corp.Full-duplex antenna system and method
US7190933 *Jul 15, 2004Mar 13, 2007Intergration Associates Inc.Method and apparatus for automatic tuning of a resonant loop antenna in a transceiver circuit
US7221243Oct 26, 2004May 22, 2007Kyocera Wireless Corp.Apparatus and method for combining electrical signals
US7221327Nov 5, 2004May 22, 2007Kyocera Wireless Corp.Tunable matching circuit
US7248845Jul 9, 2004Jul 24, 2007Kyocera Wireless Corp.Variable-loss transmitter and method of operation
US7253737Oct 18, 2004Aug 7, 2007Micron Technology, Inc.Automated antenna trim for transmitting and receiving semiconductor devices
US7265643Feb 14, 2002Sep 4, 2007Kyocera Wireless Corp.Tunable isolator
US7286012 *Jun 7, 2005Oct 23, 2007Himax Technologies LimitedOperational amplifier circuit with controllable intermediate circuitry set therein
US7292822Sep 21, 2004Nov 6, 2007Research In Motion LimitedWireless communication system using surface acoustic wave (SAW) second harmonic techniques
US7379714 *Dec 27, 2004May 27, 2008Interdigital Technology CorporationMethod and apparatus for dynamically adjusting a transmitter's impedance
US7394430Sep 14, 2004Jul 1, 2008Kyocera Wireless Corp.Wireless device reconfigurable radiation desensitivity bracket systems and methods
US7417549 *Aug 18, 2003Aug 26, 2008Keystone Technology Solutions, LlcAutomated antenna trim for transmitting and receiving semiconductor devices
US7502598 *May 27, 2005Mar 10, 2009Infineon Technologies AgTransmitting arrangement, receiving arrangement, transceiver and method for operation of a transmitting arrangement
US7509100Oct 2, 2006Mar 24, 2009Kyocera Wireless Corp.Antenna interface unit
US7512386Aug 29, 2003Mar 31, 2009Nokia CorporationMethod and apparatus providing integrated load matching using adaptive power amplifier compensation
US7548762Nov 30, 2005Jun 16, 2009Kyocera CorporationMethod for tuning a GPS antenna matching network
US7555276Dec 19, 2005Jun 30, 2009Sony Ericsson Mobile Communications AbDevices, methods, and computer program products for controlling power transfer to an antenna in a wireless mobile terminal
US7567530 *Dec 6, 2005Jul 28, 2009Pantech Co., Ltd.Method of converting communication channel in mobile communication terminal
US7711337Jan 16, 2007May 4, 2010Paratek Microwave, Inc.Adaptive impedance matching module (AIMM) control architectures
US7714676Nov 8, 2006May 11, 2010Paratek Microwave, Inc.Adaptive impedance matching apparatus, system and method
US7714678Mar 17, 2008May 11, 2010Paratek Microwave, Inc.Tunable microwave devices with auto-adjusting matching circuit
US7720443Jun 2, 2003May 18, 2010Kyocera Wireless Corp.System and method for filtering time division multiple access telephone communications
US7728693Mar 17, 2008Jun 1, 2010Paratek Microwave, Inc.Tunable microwave devices with auto-adjusting matching circuit
US7746292Sep 14, 2004Jun 29, 2010Kyocera Wireless Corp.Reconfigurable radiation desensitivity bracket systems and methods
US7747220Sep 28, 2007Jun 29, 2010Research In Motion LimitedWireless communication system using surface acoustic wave (SAW) second harmonic techniques
US7747226Apr 13, 2004Jun 29, 2010Sony Ericsson Mobile Communications AbPortable electronic devices including multi-mode matching circuits and methods of operating the same
US7761061 *May 2, 2007Jul 20, 2010Broadcom CorporationProgrammable antenna assembly and applications thereof
US7782134Feb 5, 2009Aug 24, 2010Quantance, Inc.RF power amplifier system with impedance modulation
US7795990Mar 17, 2008Sep 14, 2010Paratek Microwave, Inc.Tunable microwave devices with auto-adjusting matching circuit
US7812728Aug 27, 2007Oct 12, 2010Round Rock Research, LlcMethods and apparatuses for radio frequency identification (RFID) tags configured to allow antenna trim
US7831226 *Dec 26, 2006Nov 9, 2010Samsung Electronics Co., Ltd.Impedance matching system, network analyzer having the same, and impedance matching method thereof
US7852170Oct 10, 2008Dec 14, 2010Paratek Microwave, Inc.Adaptive impedance matching apparatus, system and method with improved dynamic range
US7865154 *Oct 8, 2005Jan 4, 2011Paratek Microwave, Inc.Tunable microwave devices with auto-adjusting matching circuit
US7884724Dec 1, 2006Feb 8, 2011Round Rock Research, LlcRadio frequency data communications device with selectively removable antenna portion and method
US7911277Oct 16, 2008Mar 22, 2011Black Sand Technologies, Inc.Adaptively tuned RF power amplifier
US7917104Apr 23, 2007Mar 29, 2011Paratek Microwave, Inc.Techniques for improved adaptive impedance matching
US7933562 *May 11, 2007Apr 26, 2011Broadcom CorporationRF transceiver with adjustable antenna assembly
US7969257Mar 17, 2008Jun 28, 2011Paratek Microwave, Inc.Tunable microwave devices with auto-adjusting matching circuit
US7982543Mar 30, 2009Jul 19, 2011Triquint Semiconductor, Inc.Switchable power amplifier
US7991363Nov 14, 2007Aug 2, 2011Paratek Microwave, Inc.Tuning matching circuits for transmitter and receiver bands as a function of transmitter metrics
US8008982Mar 11, 2010Aug 30, 2011Paratek Microwave, Inc.Method and apparatus for adaptive impedance matching
US8014732 *Jun 11, 2010Sep 6, 2011Broadcom CorporationProgrammable antenna assembly and applications thereof
US8018277Aug 20, 2010Sep 13, 2011Quantance, Inc.RF power amplifier system with impedance modulation
US8022734Aug 25, 2008Sep 20, 2011Peregrine Semiconductor CorporationLow current power detection circuit providing window comparator functionality
US8067858Oct 14, 2008Nov 29, 2011Paratek Microwave, Inc.Low-distortion voltage variable capacitor assemblies
US8099048May 12, 2010Jan 17, 2012Research In Motion LimitedWireless communication system using surface acoustic wave (SAW) second harmonic techniques
US8125399Jan 16, 2007Feb 28, 2012Paratek Microwave, Inc.Adaptively tunable antennas incorporating an external probe to monitor radiated power
US8134467May 29, 2007Mar 13, 2012Round Rock Research, LlcAutomated antenna trim for transmitting and receiving semiconductor devices
US8174315Apr 27, 2009May 8, 2012Triquint Semiconductor, Inc.Method and circuit for transforming the impedance of a load
US8190109Oct 14, 2009May 29, 2012Research In Motion LimitedDynamic real-time calibration for antenna matching in a radio frequency transmitter system
US8200168 *Aug 23, 2011Jun 12, 2012Broadcom CorporationProgrammable antenna assembly and applications thereof
US8207798Sep 9, 2009Jun 26, 2012Triquint Semiconductor, Inc.Matching network with switchable capacitor bank
US8213886May 7, 2007Jul 3, 2012Paratek Microwave, Inc.Hybrid techniques for antenna retuning utilizing transmit and receive power information
US8217731Mar 11, 2010Jul 10, 2012Paratek Microwave, Inc.Method and apparatus for adaptive impedance matching
US8217732Mar 11, 2010Jul 10, 2012Paratek Microwave, Inc.Method and apparatus for adaptive impedance matching
US8219336 *Jun 11, 2007Jul 10, 2012Rohde & Schwarz Gmbh & Co. KgArrangement for determining the operational parameters of a high-frequency power amplifier
US8219337 *Jun 1, 2007Jul 10, 2012Rohde & Schwarz Gmbh & Co. KgArrangement for determining the operational parameters of a high-frequency power amplifier
US8233851Feb 3, 2010Jul 31, 2012Avago Technologies Wireless Ip (Singapore) Pte. Ltd.Method and apparatus for providing impedance matching for high-frequency signal transmitter
US8237620Feb 1, 2010Aug 7, 2012Kyocera CorporationReconfigurable radiation densensitivity bracket systems and methods
US8260204Dec 14, 2011Sep 4, 2012Research In Motion LimitedWireless communication system using surface acoustic wave (SAW) second harmonic techniques
US8269683May 13, 2009Sep 18, 2012Research In Motion Rf, Inc.Adaptively tunable antennas and method of operation therefore
US8280323 *Oct 11, 2007Oct 2, 2012Bae Systems Information And Electronic Systems Integration Inc.Fuzzy logic control of an RF power amplifier for automatic self-tuning
US8299867Nov 8, 2006Oct 30, 2012Research In Motion Rf, Inc.Adaptive impedance matching module
US8306485 *Oct 4, 2001Nov 6, 2012Z124Device and a method for controlling and monitoring the power of the signal from a radiocommunications terminal
US8325097Jan 16, 2007Dec 4, 2012Research In Motion Rf, Inc.Adaptively tunable antennas and method of operation therefore
US8405563Feb 24, 2012Mar 26, 2013Research In Motion Rf, Inc.Adaptively tunable antennas incorporating an external probe to monitor radiated power
US8421548Nov 16, 2011Apr 16, 2013Research In Motion Rf, Inc.Methods for tuning an adaptive impedance matching network with a look-up table
US8428523Jun 24, 2011Apr 23, 2013Research In Motion Rf, Inc.Tuning matching circuits for transmitter and receiver bands as a function of transmitter metrics
US8432234Jan 12, 2011Apr 30, 2013Research In Motion Rf, Inc.Method and apparatus for tuning antennas in a communication device
US8457569May 31, 2012Jun 4, 2013Research In Motion Rf, Inc.Hybrid techniques for antenna retuning utilizing transmit and receive power information
US8463185Aug 1, 2012Jun 11, 2013Research In Motion LimitedWireless communication system using surface acoustic wave (SAW) second harmonic techniques
US8463218Mar 5, 2010Jun 11, 2013Research In Motion Rf, Inc.Adaptive matching network
US8472888Aug 25, 2009Jun 25, 2013Research In Motion Rf, Inc.Method and apparatus for calibrating a communication device
US8478205Apr 16, 2010Jul 2, 2013Kyocera CorporationSystem and method for filtering time division multiple access telephone communications
US8558633Mar 21, 2012Oct 15, 2013Blackberry LimitedMethod and apparatus for adaptive impedance matching
US8564381Aug 25, 2011Oct 22, 2013Blackberry LimitedMethod and apparatus for adaptive impedance matching
US8594584May 16, 2011Nov 26, 2013Blackberry LimitedMethod and apparatus for tuning a communication device
US8606198 *Jul 20, 2012Dec 10, 2013Triquint Semiconductor, Inc.Directional coupler architecture for radio frequency power amplifier with complex load
US8606200 *Jun 26, 2008Dec 10, 2013Intel CorporationError vector magnitude control within a linear transmitter
US8620236 *Sep 21, 2010Dec 31, 2013Blackberry LimitedTechniques for improved adaptive impedance matching
US8620246Nov 10, 2011Dec 31, 2013Blackberry LimitedAdaptive impedance matching module (AIMM) control architectures
US8620247Nov 10, 2011Dec 31, 2013Blackberry LimitedAdaptive impedance matching module (AIMM) control architectures
US8624711Jan 2, 2008Jan 7, 2014Round Rock Research, LlcRadio frequency identification device operating methods, radio frequency identification device configuration methods, and radio frequency identification devices
US8626083May 16, 2011Jan 7, 2014Blackberry LimitedMethod and apparatus for tuning a communication device
US8644776Aug 25, 2008Feb 4, 2014Peregrine Semiconductor CorporationSystems and methods for providing improved power performance in wireless communication systems
US8655286Feb 25, 2011Feb 18, 2014Blackberry LimitedMethod and apparatus for tuning a communication device
US8674783Mar 12, 2013Mar 18, 2014Blackberry LimitedMethods for tuning an adaptive impedance matching network with a look-up table
US8680934Nov 3, 2010Mar 25, 2014Blackberry LimitedSystem for establishing communication with a mobile device server
US8693963Jan 18, 2013Apr 8, 2014Blackberry LimitedTunable microwave devices with auto-adjusting matching circuit
US8712340Feb 18, 2011Apr 29, 2014Blackberry LimitedMethod and apparatus for radio antenna frequency tuning
US8744384 *Nov 23, 2010Jun 3, 2014Blackberry LimitedTunable microwave devices with auto-adjusting matching circuit
US8750810Nov 20, 2009Jun 10, 2014Qualcomm IncorporatedPower amplifier with switched output matching for multi-mode operation
US8754825 *Apr 16, 2010Jun 17, 2014Nokia CorporationControl logic for adaptive antenna
US8774743 *Oct 14, 2009Jul 8, 2014Blackberry LimitedDynamic real-time calibration for antenna matching in a radio frequency receiver system
US8781417May 3, 2013Jul 15, 2014Blackberry LimitedHybrid techniques for antenna retuning utilizing transmit and receive power information
US8787845May 29, 2013Jul 22, 2014Blackberry LimitedMethod and apparatus for calibrating a communication device
US8798555Dec 4, 2012Aug 5, 2014Blackberry LimitedTuning matching circuits for transmitter and receiver bands as a function of the transmitter metrics
US8803631Mar 22, 2010Aug 12, 2014Blackberry LimitedMethod and apparatus for adapting a variable impedance network
US20100197365 *Jun 26, 2008Aug 5, 2010Skyworks Solutions, Inc.Error vector magnitude control within a linear transmitter
US20100308933 *Aug 19, 2009Dec 9, 2010Qualcomm IncorporatedTunable matching circuits for power amplifiers
US20110063042 *Nov 23, 2010Mar 17, 2011Paratek Microwave, Inc.Tunable microwave devices with auto-adjusting matching circuit
US20110086598 *Oct 14, 2009Apr 14, 2011Research In Motion LimitedDynamic real-time calibration for antenna matching in a radio frequency receiver system
US20110254751 *Apr 16, 2010Oct 20, 2011Nokia CorporationControl Logic For Adaptive Antenna
US20110269416 *Apr 27, 2011Nov 3, 2011Renesas Electronics CorporationTransmitter
US20110269510 *May 3, 2011Nov 3, 2011Samsung Electronics Co., Ltd.Apparatus and method for preventing transmission degradation in wireless communication system
US20110310939 *Aug 23, 2011Dec 22, 2011Broadcom CorporationProgrammable antenna assembly and applications thereof
USRE44998Mar 9, 2012Jul 8, 2014Blackberry LimitedOptimized thin film capacitors
CN101331685BAug 17, 2006Nov 9, 2011索尼爱立信移动通讯有限公司Devices, methods for controlling power transfer to an antenna in a wireless mobile terminal
CN101467053BJun 1, 2007Nov 23, 2011罗德施瓦兹两合股份有限公司Arrangement for determining the operational characteristics of a high-frequency power amplifier
CN101473233BJun 11, 2007Jul 25, 2012罗德施瓦兹两合股份有限公司Arrangement for determining the operational characteristics of a high-frequency power amplifier
DE102012218900A1 *Oct 17, 2012Jan 9, 2014Htc CorporationMobiles Kommunikationsgerät und Impedanzanpassungsverfahren dafür
EP0920128A2 *Nov 23, 1998Jun 2, 1999Murata Manufacturing Co., Ltd.Impedance stabilizing unit and high-frequency module using the unit
EP1041723A2 *Mar 24, 2000Oct 4, 2000Nokia Mobile Phones Ltd.System for matching an antenna for a wireless communication device
EP1182787A1 *Aug 22, 2001Feb 27, 2002Sony CorporationMatching apparatus
EP1190405A1 *Jun 7, 2000Mar 27, 2002Johnson Controls Technology CompanyTransceiver with closed loop control of antenna tuning and power level
EP1206034A2 *Jul 20, 2001May 15, 2002Research In Motion LimitedAdaptive tuning device and method for a wireless communication device
EP1298810A2 *Sep 27, 2002Apr 2, 2003Kabushiki Kaisha ToshibaPortable type radio equipment
EP1513276A2Mar 31, 2004Mar 9, 2005Siemens AktiengesellschaftMethod for operating, and a circuit arrangement for, an amplifier in a mobile terminal
EP1732231A2 *Jun 7, 2006Dec 13, 2006M/A-Com Eurotec B.V.System and method for controlling power output from a power amplifier
EP1843477A2Mar 20, 2007Oct 10, 2007Samsung Electronics Co., Ltd.Impedance matching system, network analyser having the same, and impedance matching method thereof
EP2661031A1 *Dec 29, 2011Nov 6, 2013ST-Ericsson Semiconductor (Beijing) Co., Ltd.Method and mobile terminal for improving antenna matching performance of multi-band mobile terminal
WO2004098076A1 *Apr 23, 2004Nov 11, 2004Ericsson IncSystem and method for adaptive antenna impedance matching
WO2007005121A2 *May 16, 2006Jan 11, 2007Motorola IncWireless device and system for discriminating different operating environments
WO2007078339A1Aug 17, 2006Jul 12, 2007Sony Ericsson Mobile Comm AbDevices, methods, and computer program products for controlling power transfer to an antenna in a wireless mobile terminal
WO2008003376A1 *Jun 1, 2007Jan 10, 2008Rohde & SchwarzArrangement for determining the operational characteristics of a high-frequency power amplifier
WO2008003385A1 *Jun 11, 2007Jan 10, 2008Rohde & SchwarzArrangement for determining the operational characteristics of a high-frequency power amplifier
WO2013123155A2 *Feb 14, 2013Aug 22, 2013Microchip Technology IncorporatedProximity detection using an antenna and directional coupler switch
Classifications
U.S. Classification455/126, 455/115.1, 333/17.3, 455/123, 343/861, 455/129
International ClassificationH04B1/04
Cooperative ClassificationH04B1/0458
European ClassificationH04B1/04C
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